Malaria is a tropical parasitic disease that is a significant health threat. Each year, approximately 500 million people become infected and 2 to 3 million die worldwide. There is a great need to control the spread of this disease. Recently, the development of malaria vaccines has focused on the use of recombinant DNA technology. The inclusion of pre-erythrocytic antigens, such as the liver stage antigen-1 (LSA-1), is important in the development of a successful multi-component malaria vaccine. To date, most efforts to develop LSA-1-based vaccines have focused on the use of defined peptide sequences. Phase I research will test the feasibility of efficiently expressing truncated forms of the Plasmodium falciparum LSA-1 antigen. These recombinant subunits have the potential to provide a broader immune response than the synthetic peptides tested. The expression system proposed for this research has been shown to express high levels of recombinant proteins, including a malaria erythrocyte stage vaccine candidate antigen. The successful expression of high levels of a liver stage candidate vaccine antigen with appropriate antigenic and immunogenic characteristics could contribute to the development of a safe, efficacious and cost effective vaccine for malaria. PROPOSED COMMERCIAL APPLICATION: Malaria poses a significant health threat. Annually, approximately 500 million people become infected and 1 to 2 million die. Currently, there is no vaccine for malaria. The proposed research will test the feasibility of expressing and secreting a malaria subunit targeted for vaccine development. Successful expression of high levels of this subunit could contribute to the development of a safe, efficacious and cost effective malaria vaccine.